[ValueTracking] Filter out non-interesting conditions #118493
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This was referenced Dec 3, 2024
andjo403
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Dec 6, 2024
| class DomConditionCache { | ||
| private: | ||
| /// A map of values about which a branch might be providing information. | ||
| using AffectedValuesMap = DenseMap<Value *, SmallVector<BranchInst *, 1>>; | ||
| using AffectedValuesMap = |
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as it seems like conditionsFor is called for one DomConditionFlag value at a time maybe better add the flag as en argument and change map to store the flag as part of the key to the map?
DenseMap<std::pair<Value *, DomConditionFlag>, SmallVector<BranchInst *, 1>>;
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hmm noticed now that you mentioned that it was the calls to registerBranch that was the problem in #117442 (comment) and this will result in more work then.
but if it is the registerBranch that is the problem I assume that any filtering added will result in worse compile time.
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From some quick profiling, the impact isn't from registerBranch, but from extra DT queries in computeKnownBits. I think in principle this patch should still help as long as we don't add comparisons where both sides are variables to the KnownBits category (338d7fc#r152360307).
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This patch avoids adding RHS for comparisons with two variable operands (#118493 (comment)). Instead, we iterate over related dominating conditions of both V1 and V2 in `isKnownNonEqualFromContext`, as suggested by goldsteinn (#117442 (comment)). Compile-time improvement: https://llvm-compile-time-tracker.com/compare.php?from=c6d95c441a29a45782ff72d6cb82839b86fd0e4a&to=88464baedd7b1731281eaa0ce4438122b4d218a7&stat=instructions:u
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…7388) This patch avoids adding RHS for comparisons with two variable operands (llvm/llvm-project#118493 (comment)). Instead, we iterate over related dominating conditions of both V1 and V2 in `isKnownNonEqualFromContext`, as suggested by goldsteinn (llvm/llvm-project#117442 (comment)). Compile-time improvement: https://llvm-compile-time-tracker.com/compare.php?from=c6d95c441a29a45782ff72d6cb82839b86fd0e4a&to=88464baedd7b1731281eaa0ce4438122b4d218a7&stat=instructions:u
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This patch avoids adding RHS for comparisons with two variable operands (llvm#118493 (comment)). Instead, we iterate over related dominating conditions of both V1 and V2 in `isKnownNonEqualFromContext`, as suggested by goldsteinn (llvm#117442 (comment)). Compile-time improvement: https://llvm-compile-time-tracker.com/compare.php?from=c6d95c441a29a45782ff72d6cb82839b86fd0e4a&to=88464baedd7b1731281eaa0ce4438122b4d218a7&stat=instructions:u
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This patch avoids adding RHS for comparisons with two variable operands (llvm#118493 (comment)). Instead, we iterate over related dominating conditions of both V1 and V2 in `isKnownNonEqualFromContext`, as suggested by goldsteinn (llvm#117442 (comment)). Compile-time improvement: https://llvm-compile-time-tracker.com/compare.php?from=c6d95c441a29a45782ff72d6cb82839b86fd0e4a&to=88464baedd7b1731281eaa0ce4438122b4d218a7&stat=instructions:u
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This patch avoids adding RHS for comparisons with two variable operands (llvm#118493 (comment)). Instead, we iterate over related dominating conditions of both V1 and V2 in `isKnownNonEqualFromContext`, as suggested by goldsteinn (llvm#117442 (comment)). Compile-time improvement: https://llvm-compile-time-tracker.com/compare.php?from=c6d95c441a29a45782ff72d6cb82839b86fd0e4a&to=88464baedd7b1731281eaa0ce4438122b4d218a7&stat=instructions:u
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Address issue #117442 (comment)